My 2021 Stingray convertible has the same battery since new and have noticed a few hiccups leading me to think the 5 year old battery needs replacement. I bought an Autel OBD2 port to 12v battery memory saver and a new AC Delco 88866309 battery. A parts counter man said to not use a OBD2 saver that they will screw up modules but he also said disconnect positive cable first so I don't know if his informastion is credible. Has anyone done this or had any problems trying to save memory? Or should I just disconnect the old and install the new battery and deal with the problems that might occur?

 

You don't need the memory saver. The worst that will happen is that you may need to reindex the windows.

It is usually best practice to disconnect the negative terminal first to avoid creating an arc with the wrench by accidentally touching it to ground somewhere. Be careful with the BMS sensor on the negative terminal.

 

Do I have to disconnect the BMS sensor before removing the negative ground? I thought maybe I could leave it attached to the cable and just unbolt it. But if I have to first disconnect it, is the BMS connector release facing the frunk bin?

 

I agree he does not need to use the battery saver. But are they even safe to use? It plugs into the OBD port, and somehow is supposed to keep the system powered up enough to prevent the loss of stored data. In the case, the data that is lost, if any, is related to the window indexing. But is it even safe to be attempting to keep the car system partially powered through that port?

When the car is turned off, it does not turn off everything right away. Right after being shout down it is still drawing 10 amps, That draw drops in steps eventually dropping to a draw of 10 ma. But if the car is disturbed, it will wake up and draw more current. What happens if the battery is disconnected but the saver is providing or attempting to provide current through the OBD port? The systems can also wake up on their own for certain test. Among them, if door is opened it can trigger a brake test. Normally the car measure battery voltage when it is off as part of the process of estimating battery state of charge. What voltage will it measure with the battery disconnected, but the saver providing some voltage and current through the OBD port? It just seems to me that this should not be done unless there is actually some GM procedure for that.

 

No just pull the negative cable off first. You can leave the sensor attached.

 

I don't know whether or not is is safe to use on the car but I don't like the idea of having the positive side of the battery energized while I'm screwing around up there.

 

The procedure in the manual says remove the negative cable first. It calls the procedure for disconnecting the negative cable. The battery monitor module is connect/clamped to the negative post of the battery. The negative cable is connected to the battery monitor monitor. You can see that in the image. You loosen the clamp on the negative battery post, and move the cable and connected battery monitor aside. You will notice also that there is another wire connected to the battery monitor module. You do not need to disconnect that.

The battery saver is not needed, and may cause an issue - I don't know how it works or how it might interact with the car. I would not use it on my car.

 

Thanks for all the information. I wanted to report back that the battery change without the OBD memory saver as RKCRLR recommended, worked out without a glitch. The hardest part was getting the battery out. I let the car sit all day and I waited about 10 minutes for the frunk light to time out so there would be no load and the ECU was fully asleep. Took out all the hold downs, disconected the negative ground with the sensor attached and with a rag over the negative cable tucked it on the side careful to not damage the sensor. Also put a plastic cover over the batt terminal for insurance. Removed pos cable and pulled out the old battery on an angle. Installed the new one same way. The 5 year old battery shows 12.57v charge while the new one shows only 12.38v. Tomorrow I'm load testing the old one at Auto Zone to see if it's got a bad cell.

It started right up and DIC instructed lower and raise driver window followed by passenger window and about a minute of idle the seat adjustment came back and so did the home link. Tire pressures were still null but it seems to remember everything including bluetooth and Pandora programs. Changing the battery out was super easy. Thanks again for all the information.

 

I have the same vintage Vette and have not changed my battery. I was planning to leave my CTEK connected when changing the battery. Any problem with that?

 

Unlikely to be a problem, but also useless. The CTEK device looks for a minimum voltage from whatever it is connected to before it will even start to charge. With the battery removed, its not going to see any voltage, so it will not provide any "voltage" or allow any current to flow. I personally would not leave it connected.

 

I was told OBD2s may not be pinned right and/or may cause surges body control modules don't like. Because I've heard all these arguments doesn't mean thaey are true, but BCMs are really costly and the use of anything to supply power to your car while changing the battery isn't necessary. Even the manual says if you arent using the car for long periods you can disconnect the negative ground. When replacing it pull the plastics, unbolt the brackets and remove negative FIRST. Make sure you lift it off without sparking against the batt terminal. And be careful handling the neg cable because it has a sensor attached to it. Just put a sock over it or a cap over neg terminal so you don't arc it and tuck it on the side. Take off pos cable and pull the battery out on an up angle to the left... and it's heavy. Once you've replaced it restart the car and the display will tell you to raise and lower driver window followed by passenger window to reindex them and after couple minutes at idle everything should come back ... homelink, radio settings, seat settings, bluetooth, everything. But even if the seats need to be reset what's the problem, it beats the possibility of having computer problems. It's an easy swap without a OBD2 memory saver. If anyone uses one of these OBD2 memory savers I'd like to know, but I've searched evreywhere and didn't come across anyone using it on a C8 Corvette.

 

Update: My car had a hiccup a couple of times in the past few weeks which is why I put in a new battery. Just the same I took my 5 year old original ACDelco battery to AutoZone to have it tested and what do you know, it's 91% charged and good shape! For the $18 core charge I'll keep it on a trickle charger until I need it to jump one of my other cars. So am I an idiot for replacing it simply because it was old?

 

Not in my opinion. In the "old" days it seem that car exhibited signs of failing battery (slow cranking) before you had a hard failure. From reading many forum reports, it seem that in many cases with this car, the battery fails hard, and without prior warning. I want to replace my battery before it starts to fail, not when it fails.

 

Every 3-4 years my cars and trucks get new fresh batteries. I don’t want to replace a battery because it failed on me. I will replace them early so I NEVER have a failure.
It is cheap insurance and I don’t want the aggravation.
YMMV

 

I used to do this and always finally recycled it without ever needing it.

 

The battery in my 2021 is a little over 4 years old and is on a tender when I'm not using it for more than a week or so. It seems fine but if I ever get a slow/weak start I'll buy a new one.

 

Yes many decades ago, batteries would give you fair warning they were about to die with slower than normal engine cranking. Now my experiences with batteries over the past 25 or 30 years is that they will die with little or no advance warning. So to avoid inconvenience, proactive replacement becomes the norm based upon whatever expected life you feel comfortable.